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I've been a Canberran since moving here from Adelaide on the first day of 1980. I now live in suburban Duffy with my partner Louise Maher, ABC 666 radio and on-line journalist. Among my early memories is following Sleepy Lizards (Shinglebacks) around the paddocks north of Adelaide, guarded by the faithful bull terrier. I have always been passionate about the natural world, trying to understand how it works, how the nature of Australia came to be, and sharing those understandings. My especial passions are birds, orchids and mammals. For much of my life I have been a full-time naturalist, running bush tours, writing books etc, doing consultancies, presenting a regular radio slot on local ABC, chairing a government environment advisory committee and running adult education classes. Recently I have eased back somewhat, but am still writing, teaching, doing some radio work and running overseas tours - as part of my fascination with our Gondwanan origins I've been running tours to South America for the past decade. I was awarded the Australian Plants Society Award in 2001 and the Australian Natural History Medallion in 2006, both for services to education and conservation.

Thursday, 2 March 2017

Perito Moreno; a rare growing glacier

Perito Moreno Glacier is one of the chief attractions for visitors to Argentinian Patagonia, and quite justifiably so. It lies in the eastern fall of the Andes, some 60km west (in a straight line) of the touristy town of El Calafate, on the shores of Lago Argentino. This is a vast lake, extending all the way from El Calafate (and well beyond) to the glacier; it was 'discovered' (ie by Europeans) by Francisco 'Perito' Moreno, a nineteenth century Argentinian archaeologist, anthropologist and explorer of Patagonia. 'Perito' means an expert, and has a similar connotation to 'professor' as we might apply it respectfully to a learned person.  
The north face of Perito Moreno Glacier from approximately six kilometres away, across Lago Argentino.
The glacier lies within the huge Los Glaciares National Park, which covers some 700,000 hectares of Andean wilderness, including much of the Southern Patagonian Ice Field, the world's largest after Antarctica and Greenland. (An ice field is defined as a complex of glaciers which buries much of a mountain range.) To give a sense of scale to the photo above, the ice wall we can see towers more than 70 metres above the water surface (with another 100 metres of ice below it). The glacier arises 30 kilometres deeper into the mountains, and the final wall of ice (not all of which is visible in this shot) is five kilometres wide. 
Location of Perito Moreno, near to the Chilean border (which is within the Andes).


The map, taken from Google Earth, shows part of the ice field, the foot of the glacier (at the end of the red arrow),
Lago Argentino, El Calafate, and the approximate point from which the first photo was taken (at the yellow diamond).
This map shows too how the southern arm of the lake is cut off by the glacier pressing against the opposite shore of the lake; the water rises in the southern arm, fed by local runoff, until it is many metres above the level of the rest of the lake. Eventually (on average every five years or so) it breaks through dramatically; this aerial photo was taken on 21 March 2016, which was only three weeks after the most recent rupture. I am surmising that the pale colour of the arm is because it is normally shallower than the main body of water, but I'm open to more informed suggestions.
A closer shot of the glacier wall from the same location as the photo above.
The southern arm of the lake is in the foreground with the main lake out of sight beyond the glacier.
The first time I visited Perito Moreno, more than 10 years ago, I joined one of the daily trips which cross the lake, and conducts walks on the glacier - closely supervised by very well-informed guides, certainly on that occasion.
The boat which conveyed us - the dents in the bow were food for thought!
The ice wall becomes more impressive as the boat approaches it.
The blue in the ice develops as snow falls on the ice and is compressed by later falls, until air bubbles are squeezed out and crystals grow; ice with small crystals and air bubbles appears white. This blue was one of the things that delighted me that day - it was the first glacier I'd ever seen! Here are some images from then.
The glacier's edge, as we approached it.

Ice cave.

The view back to the lake, from atop the glacier.
Glaciers carve out landscapes, and move vast quantities of earth and rock across the surface, and the walk enabled us to see the impacts of that.
Gouges in the rock left exposed when the glacier retreats in summer; the bottom of the glacier
acts like a huge coarse sheet of sandpaper.
 
Moraine is material moved, perhaps for tens of kilometres, under the glacier and left behind when
the ice seasonally retreats. This is terminal moraine, ie at the end of the glacier.
As suggested in the post heading, Perito Moreno is most unusual in this worryingly warming world, in that it appears to be defying trends and logic, and expanding. Since the glaciologists can't agree how to explain it, I'm afraid I won't be trying to!

That was a fascinating experience, and I enjoyed it, but overall I think I prefer the walk that follows the lake shore, on a raised board walk, looking across to the glacier wall.
The glacier face; in the left foreground is the point where the southern arm of the lake (to the left) breaks through.
What is very obvious is the raft of broken ice in the water at the base of the glacier - and of course that is where it originates. 
From closer, the scale yet again becomes evident; many of the pieces of floating ice are huge.
The glacier is a slow river of ice, and at the foot ice is constantly breaking off as it it pushed by the millions of tonnes of ice behind it.
You've got to be lucky and patient to observe the moment of calving, and I was a touch too slow
to get the best of this one.
The results however are very easy to observe as they start their long journey across the lake to eventual oblivion; and some of those results are very odd indeed!
Some very singular icebergs, in which it is not hard to find animal-like shapes!

The surrounding forests are beautiful old-growth Nothofagus, or southern beech, forests, with a startling similarity to such forests in Tasmania and New Zealand - as well they might, having their origins in Gondwana when such forests stretched from a united Australia and New Zealand through Antarctica to South America - and of course were carried across the world when the continents ripped asunder. 
Old growth Nothofagus forests, above and below, straight out of ancient Gondwana...


Apart from the beeches themselves - and Nothofagus species are found in those Australian and New Zealand cool temperate rainforests - other plants are familiar too. 
Winters Bark Drimys winteri, Family Winteraceae.
This is regarded as one of the most ancient of living flowering plant families, offering an insight into
how early flowering plants may have looked. Very similar plants in Australia were until recent decades
also called Drimys, but are now known as Tasmannia.
Gavilea araucana, a member of an orchid genus of some 15 species, mostly found in the cold
far south of South America.
Close-up of the lovely flower.
Animals are present, but the busy and not always respectful hordes of tourists keep them at bay. There are always some treats however.
Patagonian Grey Fox Lycalopex griseus near the foot of the glacier.
A day in wild Patagonia would not be complete without a condor, and Perito Moreno rarely disappoints.

Andean Condor Vultur gryphus soaring against the mountains;
the snow drifts create a somewhat surreal effect.
But the highlight of my most recent visit was a much smaller predatory bird, who would probably have preferred to be overlooked...
Austral Pygmy Owl Glaucidium nana.This little owl, no more than 20cm high, hunts in a range of habitats
in the south of the continent, taking prey (mostly birds) up to twice its own size.
It is often active during the day; this one was by a busy track.
Most of my time in Patagonia has been in Chile, but my two visits to Perito Moreno stand out as highlights of my time in the wild south. Consider finding out for yourself.


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3 comments:

Kath H said...

Fascinating article with excellent explanations of glaciers... Have you seen the Drimys winter at the Botanic Gardens? It is on the corner of the 'Gondwana' plants where the main path crosses the road from the rainforest and passes the Wollemi pines. Ir has really beautiful flowers.

Ian Fraser said...

Thanks Kath, glad it was of interest. Now you mention it, I recall someone telling me that it's the only non-native plant in the gardens - would that be right? I must go and see it.

Kath H said...

It may have been me. There are a lot of non-Australian plants in that section, and of course some natives (including the Phillip Island hibiscus - technically native I suppose).